1. Field of the Invention
This invention relates to a dehumidifier and more particularly to a dehumidifier specifically adapted for use within an enclosure in which a head-disk assembly of a disk drive is disposed.
2. Description of the Prior Art
A typical disk drive is housed in a cabinet which contains a head-disk assembly, one or more power supplies, electronic circuit boards, and like components. The head-disk assembly (HDA) is disposed within an enclosure that isolates the HDA from other components in order to exclude airborne particles and like contaminants from the HDA. While active, the HDA enclosure resides at a temperature above that of the ambient temperature within the cabinet, differentials of 10.degree.-40.degree. F. being typical. When a disk drive is deactivated and the air within the HDA enclosure cools, water vapor within the relatively warm air tends to condense. Water on the parts of the HDA can have highly deleterious effects particularly on the magnetic medium.
One expedient employed to reduce or eliminate the adverse effects of moisture in a HDA enclosure upon deactivation is a chemical dehumidifier or desiccant within the enclosure. Such expedient does not eliminate problems in all cases, because the canister must be changed at regular intervals and because the desiccant can be entrained or otherwise carried by the circulating air and react with the media surfaces within the HDA to the detriment of the smoothness and integrity of the media surface.
The Peltier effect and devices exploiting it are well-known. A typical Peltier effect device has a thermocouple junction and conductors for conducting current through the junction. The junction is housed in a module that has two opposing surfaces in heat communication with the respective sides of the junction so that upon passage of current through the junction there will be a temperature differential between the two opposing surfaces of the module. These devices have been employed for heating and/or cooling electrical and other equipment. One source of such modules and related apparatus is Cambridge Thermionic Corporation of Cambridge, Massachusetts, which markets Peltier effect devices and control apparatus therefor under the trademark CAMBION.